Assessment of the Ecological State of Artificial Water Bodies in Kalmykia

The ecological state is understood as a qualitative assessment of water bodies based on the calculated value of the chemical pollution Index (CPI-10) for ten elements exceeding the MPC for fishery water bodies (MPCfw). Thirty-eight water samples taken from the five largest water bodies of Kalmykia at the same points in 2013, 2015, and 2023 have been analyzed for 70 chemical substances. Sixteen pollutants of hazard classes 3–4 have proven to be the main pollutants. The most common elements in the samples are sulfur, manganese, strontium, magnesium, copper, boron, sodium, and vanadium. The sulfur content has the maximum excess of MPCfw. The group of chemical elements of hazard classes 1–2 with excess of MPCfw in all samples is represented by beryllium, molybdenum, lead, selenium, and bromine. The exceptionally high total phosphorus levels observed in 2013 and 2015 sharply decreased in all water bodies in 2023. The ecological state of the Chogray and Krasinski drinking water reservoirs, assessed over three years, is classified as “unsatisfactory.” The Deed-Khulsun Reservoir, fed with discharge and drainage water from the Chernozemelskaya Irrigation and Water Supply System, also falls into this category. The ecological state of the Arshan-Zelmen and Tsagan-Nur reservoirs is assessed as “extremely hazardous.”